Centrifugal casting apparatus and method



i Oct. 28, 1958 JOHNSTON v v I 2,857,639

CENTRIFUGAL CASTING 'APPARAT U$ AND METHOD Filed March 26, 1957 FIG-J- INVENTOR Loyal L. Johnston United States Patent i CENTRIFUGAL CASTING APPARATUS AND METHOD Loyal L. Johnston, Zelienople, Pa., assignor to Herman Pneumatic Machine Company, Pittsburgh, Pa, a corporation of Pennsylvania Application March 26, 1957, Serial No. 648,705

Claims. (CI. 22-65) This invention relates to centrifugal casting apparatus and a method of clearing a rotating flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask.

My invention is applicable to centrifugal casting apparatus of the type disclosed in Patent No. 2,449,900. A flask open at both ends is rotatably mounted in a cradle. The flask may be rotated by any suitable source of power, such, for example, as an electric motor carried by the cradle. which the axis of the flask is generally horizontal and a position in which the axis of the flask is generally vertical. Since the means for rotating the flask is carried by the cradle the flask may be rotated in either of the positions of the cradle above mentioned and also while the cradle is moving between those positions.

At the beginning of a cycle of operation the flask is dis posed in upright position, its lower end is closed and finely divided compactable mold forming material, such, for example, as sand, is introduced into the flask through its open upper end. The flask is rotated to cause the mold forming material therein to be subjected to centrifugal action, the result being a partial compacting of the mold forming material and the formation of an axial opening therethrough. The flask is turned to generally horizontal position, the mold forming material is smoothed and compacted to form a hollow mold, molten material is introduced into the mold while it is rapidly rotated and an elongated article is centrifugally cast therein. The flask is moved back to upright position and with both the upper and lower ends of the flask open a pusher is moved into the upper end of the flask to discharge the casting through the lower end of the flask. The excess mold forming material is removed from the flask and the cycle is repeated.

The removal of excess mold forming material from the flask presents a problem in certain cases. While the above mentioned Patent No. 2,449,900 shows a flask having a radially enlarged zone at the end of the flask which is the lower end when the flask is generally upright there are occasions when the flask has a radially enlarged zone at the end of the flask which is the upper end when the flask is generally upright. When the radially enlarged zone is at the upper end of the flask there is a tendency for compacted mold forming material in the radially enlarged zone to remain in place when the pusher is introduced downwardly into the flask to discharge the casting; a portion of the radially enlarged zone a-cts somewhat in 'the nature of a shelf to retain compacted mold forming material. This problem has previously been recognized and various efforts to solve it have been made but with little practical success. The flasks have been struck with sledge hammers in an effort to dislodge the mold forming material in the radially enlarged zone at the upper end of the flask, jets of compressed air designed to blow out the mold forming material have been employed and other expedients have been resorted to but none has been satisfactory from the practical standpoint.

The cradle is shiftable between a position in Patented Oct. 28, 1958 I have solved the problem in a practical and extremely simple manner at virtually no increased cost. When the flask is moved to generally upright position near the end of the cycle for discharge of the casting the flask is still rotating slowly. I introduce into the enlarged zone at the upper end of the rotating flask adjacent the wall of the flask mold forming material dislodging means and thereby, because of the rotation of the flask, dislodge compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof. I preferably introduce into the enlarged zone of the rotating flask adjacent the wall of the flask cutting and brushing means and thereby, because of the rotation of the flask, dislodge by cutting and brush away compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof.

1 provide centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, means for rotating the flask, mold forming material dislodging means and means for introducing the dislodging flask at the enlarged zone is brushed to remove mold forming material clinging thereto. The mold forming material dislodging means is preferably shaped conformably to the inner surface of the enlarged zone of the flask, making possible the dislodging of mold forming material from substantially the entire enlarged zone of the flask throughout the entire circumference thereof.

' The dislodging means is preferably guidedly introduced into the enlarged zone of the flask adjacent the wall of the flask and means are preferably provided stopping the movement of the dislodging means into the flask when the dislodging means is slightly spaced from the wall Whereby because of the rotation of the flask compacted mold forming material may be dislodged from the enlarged zone of the flask without substantially scratching the wall of the flask.

I further provide centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, in which mold a casting having an enlargement in the portion of the mold in the enlarged zone of the flask is adapted to be centrifugally cast, means for rotating the flask, a pusher adapted to enter said end of the flask before the flask has stopped rotating to discharge the casting through the opposite end of the flask and mold forming material dislodging means connected with the pusher and projecting laterally therefrom so as to enter the enlarged zone of the flask adjacent the wall of the flask when the pusher is introduced into the flask for pushing out the casting, the dislodging means because of the rotation of the flask dislodging compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof.

The mold forming material dislodging means is preferwill become apparent as the following description of a present preferred embodiment thereof and a present preferred method of practicing the same proceeds.

In the accompanying drawings I have shown diagrammatically a present preferred mebodiment of the invention and have illustrated a present preferred method of practicing the same in which Figure l is a fragmentary diagrammatic view partly in elevation and partly in vertical cross section showing a rotating flask having a radially enlarged zone at the upper end thereof and containing a mold of compacted mold forming material having a portion in the enlarged zone of the flask and means for discharging a casting from the flask and dislodging mold forming material from said zone; and

Figure 2 is a cross-sectional view taken along the line II--II of Figure 1.

There is shown a flask 2 which is open at both ends and which is designed for the centrifugal casting of soil pipe. The flask 2 may comprise a central portion 3, an end portion 4 at one end and an end portion at the opposite end, the central portion and the end portions of the flask being fastened together in any suitable manner as well known by those skilled in the art. The end portion 4 has a radially enlarged zone designated by the reference numeral 5, said zone having a generally cylindrically end portion 6 and a generally frusto-conical portion 7 inwardly of the end portion 6. The opposite end of the flask may have a radially enlarged zone if double hub pipe is to be cast, but since that zone if present is open downwardly when the casting is charged from the flask the mold forming material therein normally is discharged along with the casting. The flask 2 is rotated by any suitable means, as, for example, an endless driving belt 3 passing about the flask between guides 9 and driven by any suitable source of power such as an electric motor and suitable driving gear mounted on the cradle in which the flask 2 is rotatably mounted. I have not shown the details of the cradle mounting for the flask since such details do not constitute the present invention. The flask may be mounted as disclosed in said Patent No. 2,449,900 except that in the present case the radially enlarged zone is at the end of the flask which is the upper end when the flask is in generally upright position while in said patent the radially enlarged zone is at the end of the flask which is the lower end when the flask is in generally upright position.

Within the flask is a mold of compacted finely divided mold forming material, the mold being designated generally by reference numeral 10. For purposes of illustration the mold 10 may be deemed to be made of sand. The mold is suitably smoothed and compacted as now well known to those skilled in the art, a portion of the mold designated by reference numeral 11 being disposed in the enlarged zone 5 of the flask. A length of soil pipe 12 is shown in the mold 11 with a hub 13 of the soil pipe in the portion 11 of the mold in the enlarged zone 5 of the flask.

The cradle in which the flask is rotatably mounted is adapted for movement between a position in which the axis A of the flask is generally vertical as shown in full lines in Figure l and a position in which the axis A is generally horizontal as shown in chain lines. As above explained the flask is disposed in horizontal position during casting. and when the material of the pipe 12 has solidified the cradle is turned to dispose the flask in generally upright position as shown in Figure 1 ready for discharge of the casting. With the flask still rotating at relatively slow speed the casting is discharged and the mold forming material 11 in the enlarged zone 5 of the flask is dislodged as will now be described.

Mounted above and in axial alignment with the flask when the flask is in upright position is a cylinder 14 within which operates a piston 15 carrying a piston rod 16 which passes through the cylinder head 17 and has its 4 forward end reduced and threaded as shown at 18. Threaded onto the threaded end 18 of the piston rod 16 is a pusher 19. The diameter of the pusher 19 is sub stantially the same as the diameter of the hub 13 of the pipe 12.

Surrounding and thus guidedly connected with the portion of the piston rod 16 which is outside the cylinder 14- and caused by gravity to rest on the pusher 19 is a sleeve 20. Screws 21 hold in place on the sleeve Ell dislodging means in the form of a bracket 28 having a mold forming material cutter 22 and a brush 23 (Figure 2}. The sleeve 20 has at least one lateral projection 24 to which is rigidly connected a rod 25 passing through a guiding and stopping bracket 26 carried by the cylinder 14 and having thereon an adjustable stop nut 27 adapted to be maintained in adjusted position by a jam nut 23. if desired for more accurate guidance a plurality of projections 24, rods 25, stop nuts 27 and brackets 26 may be provided. The cutter 22 and the brush 23 are preferably shaped conformably to the inner surface of the enlarged zone 5 of the flask 2. Figure 1 shows the shape of the cutter 22 to be the same as that of the inner surface of the enlarged zone of the flask and the cutter positioned so that when the piston 15 moves downwardly in the cylinder 14 the cutter 22 enters the zone 5 of the flask in an axial direction and lies adjacent the inner surface of the flask. The brush 23 may be similarly shaped and positioned.

The adjustable stop 27 is positioned on the rod 25 so that it comes into engagement with the top of the bracket 26 just as the cutter 22 and the brush 23 have substantially completely entered the conformably shaped radially enlarged zone 5 of the flask as the pusher moves downwardly. This stops the bracket 28 and associated mechanism as the pusher continues its downward movement. As the piston 15 moves downwardly in the cylinder 14 the pusher 19 engages the upper end of the pipe or casting 12 and pushes the pipe or casting downwardly to discharge it through the lower open end of the flask. It will be noted that the greatest diameter of the casting, even at the hub 13, is less than the smallest diameter of the flask so that the casting may be ejected downwardly through the flask. As the casting is thus ejected downwardly at least some of the mold forming material 11 tends to remain supported by the inclined portion 7 of the flask and it has been found that ejection of a casting from a flask having a radially enlarged zone at its upper end is not ordinarily accompanied by automatic discharge of all of the mold forming material in the enlarged zone of the flask. The mold forming material 11 is dislodged by the cutter 22 since the flask is still rotating when the cutter 22 enters the enlarged zone 5. Both the cutter 22 and the brush 23 are very close to the inner surface of the flask at the enlarged zone 5 and when the cutter and brush are introduced into the flask to their fullest extent the cutter lies close to but out of contact with the inner surface of the flask at the zone 5 so that it cuts away substantially all of the mold forming material at that zone without substantially scratching the flask while the brush is in contact with the wall. Thus as the flask rotates the mold forming material in the zone 5 of the flask is sub stantially completely dislodged and brushed or swept olf of the flask and falls down through the flask and out the lower open end thereof.

While I have shown and described a present preferred embodiment of the invention and have illustrated a present preferred method of practicing the same it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. A method of clearing a rotating flask having a radially enlarged zone at an end thereof and containing a mold of compacted mold forming material having a portion in the enlarged zone of the flask and a casting cast in the mold and having an enlargement in the portion of the mold in the enlarged zone of the flask, comprising pushing the casting by a pusher introduced into the flask from said end of the flask to discharge the casting through the opposite end of the flask and also introducing into the enlarged zone of the flask adjacent the wall of the flask mold forming material dislodging means and thereby, because of the rotation of the flask, dislodging compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof.

2. A method of clearing a rotating flask having a radially enlarged zone at an end thereof and containing a mold of compacted mold forming material having a portion in the enlarged zone of the flask and a casting cast for rotating the flask, mold forming material dislodging in the mold and having an enlargementsin the portion of the mold in the enlarged zone of the flask, comprising pushing the casting by a pusher introduced into the flask from said end of the flask to discharge the casting through the opposite end of the flask and also introducing into the enlarged zone of the flask adjacent the wall of the flask cutting and brushing means and thereby, because of the rotation of the flask, dislodging by cutting and brushing away compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof.

3. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, in which mold a casting having an enlargement in the portion of the mold in the enlarged zone of the flask is adapted to be centrifugally cast, means for rotating the flask, a pusher adapted to enter said end of the flask before the flask has stopped rotating to discharge the casting through the opposite end of the flask and mold forming material dislodging means connected with the pusher and projecting laterally therefrom so as to enter the enlarged zone of the flask adjacent the wall of the flask when the pusher is introduced into the flask for pushing out the casting, the dislodging means because of the rotation of the flask dislodging compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof.

4. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, means for rotating the flask, mold forming material dislodging means and means for introducing the dislodging means into the enlarged zone of the flask adjacent the wall of the flask whereby because of the rotation of the flask compacted mold forming material may be dislodged from the enlarged zone of the flask throughout the entire cirumference thereof.

5. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, means for rotating the flask, mold forming material dislodging means and brushing means, and means for introducing the dislodging means and brushing means into the enlarged zone of the flask adjacent the wall of the flask whereby because of the rotation of the flask compacted mold forming material may be dislodged from the enlarged zone of the flask and the wall of the flask at the enlarged zone brushed to remove mold forming material clinging thereto. 7

6. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, means for rotating the flask, mold forming material dislodging means shaped conformably to the inner surface of the means and brushing means, means for guidedly 'introducing the dislodging means and brushing means into the enlarged zone of the flask adjacent the wall of the flask and means stopping the movement of the dislodging means and brushing means into the flask when the dislodging means is slightly spaced from the wall and the brushing means is in contact with the wall whereby because -of the rotation of the flask compacted mold form ing material may be dislodged from the enlarged zone of the flask and the wall of the flask at the enlarged zone brushed without being substantially scratched to remove mold forming material clinging thereto.

8 Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zoneof the flask, means for rotating the flask, mold forming material dislodging means shaped conformably to the inner surface of the enlarged zone of the flask and brushing means, means for guidedly introducing the dislodging means and brushing means into the enlarged zone of the flask adjacent the wall of the flask and means stopping the movement of the dislodging means and brushing means into the flask when the dislodging means is substantially fully inserted into the enlarged zone of the flask but slightly spaced from the wall and the brushing means is in contact with the wall whereby because of the rotation of the flask compacted mold forming material may be dislodged from substantially the entire enlarged zone of the flask and the wall of the flask at the enlarged zone brushed without being substantially scratched to remove mold forming material clinging thereto.

9. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, in which mold a casting having an enlargement in the portion of the mold in the enlarged zone of the flask is adapted to be centrifugally cast, means for rotating the flask, a pusher adapted to enter said end of the flask before the flask has stopped rotating to discharge the casting through the opposite end of the flask and mold forming material dislodging means guidedly connected with the pusher and movable therewith as the pusher enters said end of the flask, the dislodging means projecting laterally from the pusher and entering the enlarged zone of the flask adjacent the wall of the flask as the pusher pushes out the casting, the dislodging means because of the rotation of the flask dislodging compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof, the dislodging means stopping at the enlarged zone of the flask While the pusher continues its movement to push out the casting.

10. Centrifugal casting apparatus comprising a flask having a radially enlarged zone at an end thereof adapted to contain a mold of compacted mold forming material having a portion in the enlarged zone of the flask, in

which mold a casting having an enlargement in the portion of the mold in the enlarged zone of the flask is adapted to be centrifugally cast, means for rotating the flask, a pusher adapted to enter said end of the flask before the flask has stopped rotating to discharge the casting through the opposite end of the flask, mold forming material dislodging means shaped conformably to the inner surface of the enlarged zone of the flask guidedly connected with the pusher and movable therewith as the pusher enters said end of the flask, the dislodgingmeans projecting laterally from the pusher and entering the enlarged zone of the flask adjacent the wall of the flask as the pusher pushes out the casting, the dislodging means because of the rotation of the flask dislodging compacted mold forming material from the enlarged zone of the flask throughout the entire circumference thereof, and means stopping the movement of the dislodging means into the flask when the dislodging means is substantially fully inserted into the enlarged zone of the flask but slightly spaced from the flask while the pusher continues its movement to push out the casting whereby because of the rotation of the flask compacted mold forming material may be dislodged from substantially the entire enlarged zone of the flask without substantially scratching the flask.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2,857,639 October 28,, 1958 Loyal L, Johnston It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 5 for "mebodiment" read embodiment line 31 for "charged" read discharged =0 Signed and sealed this 3rd day of February 195 590 (SEAL) Attest:

KARL Ho AJQINE ROBERT C. WATSON Attesting Oficer Commissioner of Patents 

